Universal flexible sheath with bellow for articulated joint and equipment for fixing same

ABSTRACT

The invention concerns a universal flexible sheath with bellow for articulated joint and equipment for fixing said sheath. The protective sheath consists of a tubular element ( 4, 5, 6, 7, 8 ) with fixing zones at its ends and a central conical bellow ( 1 ), whereof the folds comprise sloping flanks forming an angle of 0 to 45° with the sheath axis on the large diameter side and of 60 to 80° on the small diameter side, said sheath being associated with flexible or ductile mounting cones whereof the base diameter is variable. The invention concerns equipment for repair shops and the sheath is designed for protecting lubricated joints for transmitting movement to mobile members, and in particular to transmission elements in motor vehicles.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a universal flexible sheath with bellows for anarticulated joint and a device for insalling the same.

The invention relates to the industrial and commercial area of themanufacture and distribution of equipment for motor vehicle repair andmaintenance shops. The sheath is used for protecting lubricated jointssuch as universal joints, constant velocity joints,three-ball-and-trunnion universal joints, ball joints, socket joints, orsimilar joints used for transmitting movement to mobile members. Theinstalliation device can be adapted to all types of protective sheaths,and particularly to those used for mechanical transmission componentssuch as steering racks.

Protective sheaths for articulated joints serve for protecting thearticulations against foreign bodies, impacts and other externalelements. They also serve to contain in a leakproof manner, thelubricating mass that the mechanism needs in order for it to last.

The sheath utilizes by a tubular element made of rubber or flexibleelastomer, which can be conventionally molded in a single piece andformed of a conical central part having ridges that permit flexing andaxial extension of the body. The tublar element has two ends, eachhaving cylindrical fixing zones with an inner diameter enabling the endsto be attached to the corresponding components of the articulated joint.The ends will also utilize grooves which act as forming seats intendedfor receiving clamping devices so as to ensure the leak tightness of theassembly.

2. Description of Background and Relevant Information

Most sheaths are specific for each application, particularly foroutfitting new vehicles. In order to reduce the number of references onthe replacement market, some models are “universal”, i.e. they can bemounted on a wide range of articulated joints having different diametersand lengths. This “universality” is achieved, specifically, by means ofmultiple, stepped fixing zones, as disclosed in patent document EP 0 339387, for example, which relates to a protective bellow for thearticulated joints of a mechanical transmission. The sheath utilizesseveral fixing zones of different diameters at each end.

In use, the protective sheaths are subject to constant distortion inlength and inclination, while also being subject to rotations of veryvariable speed. Under the effect of centrifugal force and distortion ofthe wall of the sheath, the lubricating substance tends to migrate awayfrom the parts of the joint near the axis of rotation and thearticulation mechanisms, which, in case of leakage or improper filling,may seriously compromise the functioning or life of the joint.

In the case of replacement sheaths, and in order to avoid disassemblingthe transmission assembly, installing the protective sheaths in itsproper position is generally done by means of a rigid hollow mountingcone with or without expander rings, such as those described in patentdocument FR 2 727 644. This reference presets a sheath installing devicecomprising a hollow cone whose base may be expanded as needed by meansof a series of conical rings mounting up on the cone, the dimensions ofwhich correspond to the different diameters of the articulated joints tobe equipped with a protective sheath.

The base of the cone is placed around the spherical mounting or “bowl”that is the largest diameter element of the articulated joint, ontowhich the bellow is slid by forcing so as to move it far enough for itswidest end to come into position on the periphery of the element. Inthis manner, the cone serves to facilitate the intense stretching thatthe bellows must undergo. When it reaches the end of the cone, thesheath retracts suddenly to assume a position on the proper side of thebowl or spherical mounting.

These conventional cones are both rigid and cumbersome; they requiredifferent diameters depending on the universal joints found in themarket, and are, therefore, relatively expensive.

SUMMARY OF THE INVENTION

The invention makes it possible to provide protective sheaths forarticulated joints in which the distortion of the outer wall causesdrifting of the grease contained in the sheath in the direction of thegreater diameter of the sheath, i.e., toward the area where themechanical elements requiring lubrication are located (brackets, joints,mechanical bearings, etc.). The invention also provides a sheathinstallation device in the form of a mounting cone that is bothadaptable and minimally cumbersome for installing sheaths.

The invention provides a protective sheath having a tubular element withfixing zones at the ends and a conical central bellows, the folds of thebellows have sloping flanks forming an angle of 0 to 45° with the sheathaxis on the large diameter side of the sheath and of 60 to 80° on thesmall diameter side, so that the distortion of the sheath causes a backflow of the grease toward the large diameter end. The sheath may beconnected to the flexible or ductile mounting cone wherein the basediameter is variable.

BRIEF DESCRIPTION OF THE DRAWINGS

In the attached drawings, provided by way of example but not limitingthe embodiments of the object of the invention,

FIG. 1 is an axial half section of a protective sheath for transmissionjoint,

FIG. 2 shows a sheath of the same type, at a different scale, mounted onan articulated joint,

FIG. 3 shows a side view of a protective sheath for steering rack,

FIG. 4 is an enlarged view of detail D2 of the previous figure,

FIG. 5 is an enlarged view of detail D1 of FIG. 2,

FIGS. 6 and 7 show, in the same conditions, a variant of a sheath thatcan be mounted on transmission joints with or without a peripheralgroove as an attachment rib, respectively,

FIG. 8 shows a flat view of a foil that can be wrapped to form amounting cone for a protective sheath,

FIG. 9 shows the foil of FIG. 8 after being wrapped,

FIGS. 10 and 11 are side and perspective views, respectively, of anextensible mounting cone, and

FIG. 12 shows a mounting cone made integral with the protective sheath.

DETAILED DESCRIPTION OF THE INVENTION

The sheath, FIGS. 1 through 5, has a tubular sleeve made of a flexiblematerial resistant to lubricants, such as rubber or elastomer, and hasthree parts: a central, conical, flexible, and extensible bellows 1 andtwo ends 2, 3 allowing the sheath to be mounted in a leak tight manneron the articulated joint.

The ends 2 and 3 form fixing zones having a small and a large diameter,respectively, each having one or more essentially cylindrical elements4, 5, 6, 7 and 8, 9, 10 of different inner diameters, equipped withouter grooves for accommodating a clamp that ensures the leak tightnessof the assembly. These cylindrical elements may be connected to eachother by means of ductile ridges 11.

The outer support surfaces of the clamp may be smooth or, they may havecircular grooves 12 transmitting differential compressions, resulting inbetter leak tightness.

The folds of the sheath 1 have sloping flanks along angles that areasymmetric with respect to the longitudinal axis of the sheath: on theone hand, on the large diameter side, angles A1 ranging from 0 to 45°and, on the other hand, on the small diameter side, angles ranging from60 to 80° with respect to the same longitudinal axis. When the sheath issubject to rotation or bending movements, the grease that is in thesheaths which are known in the art, tends to leak from the articulation13 and move toward the small diameter of the sheath. However, in thesheath of the invention, the grease is pushed back toward thearticulation. In fact, the open angles A2 (60 to 80°) tend to form amobile barrier, while the closed angles A1 (10 to 30°) promote thepassage of the lubricant.

Makers of vehicles, which are equipped with power steering provide ventsto equalize the pressure differences that exist between the twoprotective sheaths with bellows mounted at each end of the steeringrack. These vents are linked to each other by tubes having variablediameters and configurations, which depend on the vehicle model. In allknown cases, these tube vents are connected to the protective sheaths,or cross through them. The adaptable sheaths conventionally available onthe market do not have an opening or attachment for these tube vents.The difficulty with the conventional sheaths lies in the great disparityof mounts selected by the vehicle makers, and in the complexity ofmolding a protective sheath that is truly adaptable.

The protective sheaths according to the invention intended for steeringracks are equipped with a flexible connector 14 located so that it canbe connected to the great majority of tube vents of vehicles currentlyon the market. The open end of this connector has several sections ofdifferent diameters that make it possible to connect the different tubesthat exist on the market to it, by simple means of clamping. The otherend is closed to allow the sheath to be mounted on mechanical steeringracks that, consequently, do not have a vent. This closure is obtainedby means of a cap 15 made integral with the sheath during molding. Thiscap can easily be removed or pierced by the installer in cases of powersteering, such as when there is a tube vent, so that it is made tocommunicate with the inside where it is used on the sheath (FIGS. 3 and4).

In order to be economically viable, the assembly must be made in onepiece, by simple injection or by injection-blow forming in conventionalequipment opening in two planes. This is made possible by thepositioning and shape of the flexible connector 14 and, particularly, bythe position of the cap 15 which is made integral with the wall of thesheath.

The inner surface of conventional protective sheaths has, in general,cylindrical fixing elements 4 through 10, which can be circularattachment ribs 16 generally placed at the middle of each supportsurface. These ribs are intended to engage in peripheral grooves 17provided on the “bowl” 13 of the articulated transmission joints orsteering racks. Very often, these grooves are positioned near the edgeof the joint at issue, such that the support surface 18 of thecylindrical element is partly offset. In order to avoid the risk ofdismantling, the attachment ribs 16 of the protective sheaths accordingto the invention are displaced toward the bellow 1 so that the clampsbear on a flat area and cannot tilt (FIG. 5).

Some bowls 13 of articulated joints, or racks, do not have a peripheralgroove 17. In order to be truly universal, replacement sheaths must beable to adapt in all cases. If the inner fixing surface of the sheathhas an attachment rib 16, it is difficult to mount it on a smoothsurface; in the opposite case, fixing will be more secure by reason ofthe small bearing surface of bowls having a peripheral groove.

In order to permit the protective sheath according to the invention toadapt to all types of bowls or racks, whether they have a peripheralgroove 17 or not, some fixing areas 4-10 advantageously will have aV-shaped annular fold 20 pointing toward the inside, instead of and inplace of an attachment rib, the shape of which is determined so that itpermits the fold to penetrate into the peripheral groove 17 of theelements that have one (FIG. 6), or to the contrary to open out andbecome flattened when the clamp 21 is fixed in cases of the elementshaving a smooth outer surface (FIG. 7). The folds 20 will preferably beframed by two flat cylindrical areas bearing on the outer surface of thebowl or racks case.

Rigid mounting cones are known in the art and will advantageously bereplaced by devices for installing the sheath that adapt automaticallyto the diameter of each bowl 13 of a transmission joint or steering rackcase.

The first embodiment of this automatic cone has a simple circularsemi-rigid foil 22, made of thermoplastic for example, cut out from aflat sheet, pierced by a hole at the center, and split along a radius orcut in a pie shaped sector. This foil is then wrapped to assume aconical shape which, when placed onto the transmission joint or steeringarm, makes it possible to install the protective sheath smoothly. Toprevent the conical foil from passing to the other side of the bowl 13or spherical mounting of the steering along with the sheath, stops thatcan be molded 23, or the stops can be flexible strips 24 cut in the foil19. Depending on the quality selected by the maker, this simple foil canthen be discarded or reused after use (FIGS. 8 and 9).

Another embodiment of an automatic mounting cone comprises an extensiblesemi-rigid cone 25 having a section of hollow sawteeth 26 along all orpart of its length. These sawteeth relax or retract as a function of thediameter of the transmission joint bowl 13, and are designed so thatthey never present sharp edges toward the below forced over them. Ofcourse, inner edges can be provided, in the form of curved fluting ortubular structures so as to prevent the cone from moving along with thesheath as it passes over the “bowl”. With the mounting cones known inthe art, the lubricated sheath tends to move toward the small diameter.To remedy this, the installation device according to the invention has acylindrical section 27 extending the end of the cone having the smallerdiameter, and on which the sheath can be placed prior to fixing it inposition, which facilitates the mounting operation (FIGS. 10 and 11).

The advantages of this device, as in the previous embodiment, areseveral:

A single cone can be used for all articulated joints.

Minimal effort is required to force the passage of the flexible sheath,regardless of the diameter to be crossed.

It can be molded in a single piece.

According to a third variant of an embodiment, the flexible sheath has abuilt-in mounting cone 28, the cone and the sheath being molded in asingle piece are integral, either by two-material flexible injectionutilises a material for the sheath, and a semi-rigid material for thecone- or by single-material injection. The sheath, on its small diameterside, is extended by a slit or a closed cone that is smooth or striated,and may have a sawtooth structure, or be ridged. During mounting, thecone is placed on the bowl 13 of the articulated joint, and the sheathis turned back on itself before being forced over the built-in cone 28,thus the cone permits smooth extension of the sheath over the bowl. Theinstaller may disconnect the cone from the sheath by a simple cuttingaction either before or after passage over the bowl of the articulatedjoint (FIG. 12).

The positioning of the various constitutive elements gives the object ofthe invention a maximum number of advantages that have not been achievedso far through similar devices.

What is claimed is:
 1. A flexible sheath comprising: a conical centralbellows for an articulated joint for protecting lubricated joints andfor transmitting movement to mobile members; said flexible sheathfurther comprising a tubular element; wherein the tubular elementfurther comprises at least one fixing zone on each end; said tubularelement further comprising said conical central bellows; each said atleast one fixing zone further comprising an outer clamping surface forreceiving a clamp and an inner surface comprising at least oneattachment rib, wherein the at least one attachment rib is located onthe inner surface of the at least one fixing zone at a position otherthan a middle of the outer clamping surface and offset towards theconical central bellows.
 2. The flexible sheath of claim 1, wherein theouter surface of said at least one fixing zone comprises circulargrooves for transmitting differential compressions and improving leaktightness.
 3. A combination comprising: a steering rack; and at leasttwo protective sheaths for a steering rack, each of said at least twoprotective sheaths comprising: a flexible connector having an open endprovided with several sections of different diameters for compensatingfor the differences in pressure that exist between the two protectivesheaths, each protective sheath having a bellows mounted at each end ofthe steering rack; wherein one end of the flexible connector includes acap which is integral with the wall of the sheath such that it can beeasily removed or pierced when used on a power steering, so as to enablethe sheath to be mounted on non-assisted mechanical racks.
 4. Theflexible sheath of claim 1, wherein the conical bellows comprises aplurality of folds each having sloping flanks defined by asymmetricalangles with respect to the longitudinal axis of the sheath; said anglesfacilitating movement, when the bellows is subject to rotation orbending movements, of any lubricant contained in the sheath toward alarge diameter end of the sheath.
 5. A device for installing a flexiblesheath on an articulated joint comprising: one of, a flexible or ductilemounting cone; said mounting cone having a base diameter for installinga sheath; said sheath having different diameters of articulations foruse in transmission joints or steering rack cases.
 6. The device ofclaim 5, wherein the mounting cone comprises a semi-rigid circular foilmade by the process of: cutting a circular shape from flat sheet stock;punching a center hole; removing a pie shaped section; and wrapping thefoil to form a cone that can be placed on an articulated joint orsteering arm in order to facilitate installation of the protectivesheath.
 7. The device of claim 5, wherein the mounting cone comprises asection of hollow sawteeth such that the sawteeth can relax or retractas a function of the diameter of the articulated joint, and wherein thesheath is devoid of sharp edges which can damage the flexible sheathwhile it is being installed.
 8. The device of claim 7, wherein themounting cone comprises a cylindrical section extending to a smalldiameter end for accommodating the flexible sheath prior to itsinstallation.
 9. The device of claim 5, wherein the mounting cone andflexible sheath are interally molded in a single piece by any one of thefollowing methods: by two-material injection, flexible for the sheathand semi-rigid for the cone, or by single-material injection, said coneextending said sheath on the small diameter side and capable of beingseparated from it by a simple cutting action, either before or after itis fixed in position.
 10. The device of claim 5, wherein the mountingcone comprises stops on its inner face for engaging the articulatedjoint in order to prevent the cone from being moved by the flexiblesheath; wherein said stops are integrally molded with the cone.
 11. Theflexible sheath of claim 1, wherein the lubricated joints comprise atleast one of: universal joints, constant velocity joints,three-ball-and-trunnion universal joints, ball joints, socket joints, orsimilar joints.
 12. The flexible sheath of claim 1, wherein thearticulated joint comprises mobile members, said mobile memberscomprising steering racks used for motor vehicle replacement equipment.13. A flexible sheath for an articulated joint comprising: a centrallylocated conical bellows; said sheath further comprising a tubularelement for retaining contents therein and formed with at least twofixing zones on at least one end; said tubular element having an insidesurface and an outside surface; and one of the two fixing zones having adifferent diameter than a diameter of another of the two fixing zones,at least one of the two fixing zones further comprising an outerclamping surface for receiving a clamp and an inner surface comprisingat least one attachment rib, wherein the at least one attachment rib islocated on the inner surface of the at least one fixing zone at aposition other than a middle of the outer clamping surface and offsettowards the conical bellows.
 14. The flexible sheath of claim 13,wherein the at least one attachment rib is located on the inside surfaceof each fixing zone.
 15. The flexible sheath of claim 13, furthercomprising at least one external attachment being located on the outsidesurface of the at least one fixing zone.
 16. The flexible sheath ofclaim 13, wherein the outside surface of at least one fixing zonecomprises a clamping area having sides of greater diameter than theoutside surface of the at least one fixing zone.
 17. The flexible sheathof claim 13, wherein the outside clamping surface has at least onecircular groove formed therein for transmitting differentialcompressions suitable for reducing leakage.
 18. The flexible sheath ofclaim 13, wherein the conical bellows further comprises a plurality ofsections having varying cylindrical diameters.
 19. The flexible sheathof claim 11, wherein the sheath further comprises a flexible connectorfor pressure compensation.
 20. The flexible sheath of claim 19, whereinthe flexible connector is closed by a cap.
 21. The flexible sheath ofclaim 19, wherein the sheath is formed integrally with a flexibleconnector.
 22. The flexible sheath of claim 13, wherein the conicalbellows further comprises folds.
 23. The flexible sheath of claim 22,wherein the sheath contains a lubricant and the folds comprising slopingflanks are formed at asymmetrical angles with respect to thelongitudinal axis of the sheath; wherein the angles facilitate thelubricant contained with the sheath to move in the direction of greaterdiameter.
 24. A mounting cone for installing a flexible sheath on anarticulated joint comprising: a tapered tubular member which is, one of,flexible or ductile; said tapered tubular member having at least oneintegrally formed stop for engaging the articulated joint; wherein themounting cone facilitates the installation of a flexible sheath on anarticulated joint.
 25. The mounting cone of claim 24, wherein thetubular member comprises a semi-rigid circular sheet having a pie shapedsection removed.
 26. The mounting cone of claim 25, wherein thesemi-rigid circular sheet comprises a foil.
 27. A mounting cone forinstalling a flexible sheath on an articulated joint comprising: atapered tubular member which is, one of, flexible or ductile; saidtapered tubular member having a plurality of integrally formed hollowsawteeth; wherein the hollow sawteeth can relax or retract as a functionof the diameter of the articulated joint.
 28. The mounting cone of claim27, wherein the tapered tubular member is integrally formed with theflexible sheath.
 29. The mounting cone of claim 28, wherein the tubularmember and flexible sheath are injection molded.
 30. The mounting coneof claim 29, wherein the tubular member and flexible sheath areseparable from one another.
 31. The mounting cone of claim 30, whereinthe tubular member and flexible sheath are separable from one another bycutting.
 32. The mounting cone of claim 27, wherein the tapered tubularmember has at least one integrally formed stop for engaging thearticulation joint.
 33. The mounting cone of claim 32, wherein the atleast one integrally formed stop for engaging the articulation joint isdisposed on the inside surface of the tubular member.